The present invention relates to electronic locking systems, and more particularly to electronic locking systems of a type including a reprogrammable key which electronically and mechanically interacts with a reprogrammable lock cylinder.
Electronic security systems have been well known for a number of years, and recent years have seen the marriage of electronic technology with traditional door locking devices such as mortise locks. Some of the early commercial systems have required a hard-wired connection between a central processor and the electronics of the locking systems of given doors. A disadvantage of such systems is the requirement of cable connections between the central controller and individual lock assemblies. This requires expensive remodelling, and such installations are vulnerable to tampering.
Other systems integrate hardware elements for control of functions of locking systems within the lock assembly itself, typically by housing circuit boards, power supplies, etc. within the door or in a module attached to the door. This approach also requires considerable remodeling of the installations to adapt to the specifications of the given locking systems. There is a need for improved locking systems which permit retrofitting of locking assemblies of a type compatible with traditional installations, thereby facilitating the conversion from traditional mechanical locking systems to electronic locks.
The use of innovative techniques for coding locks, such as for example optical, magnetic, electronic, and other techniques, offers the possibility of a number of significant advantages as compared with mechanical bitting. Electronic coding and the like holds the promise of increased information content with attendant improvements to system capabilities; the flexibility of recoding the cylinder or key (or both); networking with other electronic systems of an installation; effective new countermeasures against "lock-picking" attempts; and developments of versatile management systems for hotels and other institutions. Prior art electronic locking systems have just begun to realize some of these advantages, and are hindered by limitations on the loads of information in change between key and lock.
U.K. Patent Application GB No. 2112055A and Australian Patent Application AU-A No. 21588/83 disclose combination mechanical/electronic lock cylinders including a "rotor" (cylinder plug) and "stator" (cylinder shell). The stator houses a solenoid-actuated locking bolt which is oriented parallel to the keyway and which has a retaining member at one end. The retaining member mates with a grooved blocking member fixed to the rotor, the cam groove being profiled to include a "blocking notch" (in 2112055A) or "retaining ring" (in No. 21588/83) which prevent rotation of the rotor in certain states of the solenoid.
U.K. Patent Application GB No. 2155988 A discloses a mechanical/electronic key in which an electronic assembly (such as a dual-in-line standard package integrated circuit) is mounted in a casing which serves as the key grip. The casing is fixed to the key shank and includes a connecting part for electrical contacts. This application does not show the use of electronically eraseable programmable read-only-memory (EEPROM) for strong keying code, nor the mounting of an IC directly to the key shank.
It is a primary object of the invention to provide an electronic door locking system type including a self-contained lock cylinder. A related object is to design a system of this type which is compatible with pre-existing mechanical lock installations, facilitating conversion from mechanical to electronic locks.
Another object of the invention is to design a reliable locking system. Such system should avoid failures due to a variety of physical conditions, such as mechanical stresses, poor electronic connections, and electrostatic discharges.
Desirably such system should be a purely electronic one, i.e. not dependent on mechanical bitting or the key to open the lock cylinder.
Still another object is to provide the ability to electronically transfer information from the key to the cylinder, and from the cylinder to the key. A related object is to permit recoding of the cylinder by the key, and vice versa. Such a system should be versatile in operation, allowing multilevel master keying and a variety of other significant keying functions.